I don't think there is a such thing as escape proof.
There have been numerous prisons throughout history that have been labeled escape proof and proven wrong. Any security measure can be bypassed with the right resources.

An accomplice seduced him in a bar and injected him with either a metal or a substance that increased the iron content of his haemoglobin. Can't remember which, and I seem to recall that in reality blood-borne iron isn't magnetic.

An accomplice seduced him in a bar and injected him with either a metal or a substance that increased the iron content of his haemoglobin. Can't remember which, and I seem to recall that in reality blood-borne iron isn't magnetic.

well i think she put so much in him that it didnt bond with the blood stuff.. or whatever.. so yea then magneto is like WTF there is iron in your blood, gimme it plz and he took it

To play the nerd here, I remember something about there being a calculable probability that you can undergo quantum tunneling and move intact from one location to another. While the odds are slim, I think that no prison can be entitled escape proof until they learn to deal with this possibility. Force fields perhaps?